Ask HN: How does LinkedIn know so much about me?

[MrSteve1212]

So browsing through my linked in account, it does a great job of recommending people I know (people I graduated with ... people from work, etc).

Here's the thing though, it's too good. For example, it just recommended I connect with a SCUBA instructor I met with once in Florida. I saw this guy once, 2 years ago, haven't seen him since and have no other connections to him. The only way I can figure this out is if they somehow have access to my gmail account. I'm fairly certain I never connected gmail to linked inn, and even if someone did, surely they don't have permission to parse their entire e-mail history...

How do they know so much?

[highlander]

Is it possible that he gave LinkedIn access to his email account and he has your address in his email? Alternatively, could he have viewed your LinkedIn page? Maybe LinkedIn recommend connections that way also.

[MrSteve1212]

I doubt he viewed my page (I was a random customer from years ago), but the fact that he might have connected his e-mail account sounds plausible.

[joezydeco]

LinkedIn is definitely doing something with your searches. I've searched for old high school/college friends (sure, ex-girlfriends too, you got me), only to have them pop up in the recommendation box a few months later.

Who's to say that LinkedIn isn't adding those people to some secondary network for you and later making recommendations off the people they are searching for?

[bartonfink]

On the flip side, I'd like to know how they seem to consistently miss one of the most important pieces of information about my career: I'm leaving the U.S. soon. I'm planning to emigrate in the next three years, either to Australia or New Zealand. I've made a few LinkedIn connections with folks there (hi, Duncan and Steve!). I've joined LinkedIn groups for software professionals in both countries. I subscribe to Google Groups for the same purpose. I regularly search LinkedIn's company listings for software companies in both countries that I'd like to keep my eye on. I have literally come right out and told them this in feedback about their apps.

LinkedIn has access to all of this data about me that really should be setting off alarm bells in their recommendation systems, and yet it's not happening. I'm constantly given recommendations for companies, groups and jobs I might be interested in in various areas of the U.S., and none of them take that fact into consideration.

How can they miss this?

[revorad]

Sounds like they have developed tech similar to Katango - http://www.building43.com/videos/2011/07/12/katango-organizi...

And now Google probably also knows that much about you because they bought Katango.

LinkedIn also bought Rapportive recently, so they have a very high quality people database.

[relaunched]

I have similar concerns. A referral from a friend of a friend, led to an email exchange...and nothing ever came of it. However, 2 years later, the guy is a suggested connection on linkedin.

Highlander is probably right. I doubt there is an instance where major providers are exchanging information behind closed doors. But if there is, it won't be long before it comes into the light of day.

[joelmaat]

I've noticed the same thing. How could they possible know that I know of these people I see. Perhaps they do look at who I view, and who views me.

Its quite disturbing, but at the same time fairly impressive. I'm very curious.